Manufacturing froth fillings.



- comparatively high internal pressure of the "UNITED STATES PATENT OFFICE.

FRITZ PFLEUMER, .OF DBESDEN, GERMANY ANUFACTURING ruo'rn FILLINGQS.

1 ,167.518. No Drawing.

To all whom it may concern: I I

Be itknown that. I, Fnrrz PFLEUMER, a subject of the Emperor of Austria-Hungary, residing at Dresden, Germany, have invented certain new and useful Improvements in .Manufacturing .Froth Fillings, of which the following is a specification.

-ThlS invention relates to the manufacture of froth fillings for tires and the like by vulcanizing the/material (india rubber,- guttapercha', or balata) at about 136 (3., coolgas filling.- I v The drawbacks attendingftheuse of this fillingas hitherto manufactured are due to thefact that-it is not advisable to compress the froth afterit has been expanded to at- I mos'pherio pressure, for the purpose of obtamlng higher gas pressure. In practice this is possible only to quite small pressures of about 1% atmospheres, since considerable difficulties are encountered in forcing greater volumes of the froth into an. envelop,

'suchas a tire tube. Moreover the froth containing gas under pressure was manufactured in such a manner that'it was not at once expanded after the vulcanization, but allowed to cool under pressure for several hours. If the froth is to be used as tire filling, then, although the material already contains gas under pressure, it is necessary togive it a somewhat greater volume than that corresponding to the space it occupies inside the tire; otherwise the filling would work loose in the tire during running, and the re-- sulting friction between the tire and the filling would soon destroy the latter. For the same reason it is necessary to allow the filling the possibility of expansion in view of the expansion of the tire. The applicatlon of such froth containing gas under pressure,

under these conditions is attended with several drawbacks in'practice. First, as soon as a high gas pressure obtains in the tire'it is very difiicult to properly force suflicient fillings into the tire and confine the same therein by the ordinary method of urging Specification of Letters Patent.

' found that the filling,

together of the tire edges or that of the interiorof the tire;

' Patented Jan. 11, 1916.]

Application filed August 12, 1912. Serial No. 714 811.

the free edges of the tire toward each other. Secondly, a froth filling manufactured in this manner is continuously stressed, that is each fil efi'ect ofa tension originatin from the in ternal pressure of the gus filhng; This ten-j slon is reatly increased by the efiect of me,-

chenica working when the action. Since this filling is expansion nearly to thex'permis'sible limits,- the additional efiects due to the'working of the'tire increase the stress much beyond the' allowable continuousfilled tire in dition' is destroyed after quite ashortlife (in bicycles 600-1000 1011.). Thi-rdly, with fillings brought into position by the forcing headings, these latter do not lie properly;

thetire instead of lying along the'bottom of the rim, that is'they tend to curl when placed into position in such'a manner that the necessary amount of gas for the inflation of the tire, although beforebeing put in position the filling has a volume as small as the filling after being placed in position being released from the tension resulting from the compressed gas. i

- The invention consists substantially in a process of the kind referred to in which the filling material is cooled under a gas pressure equal tool-higher than that of the vulcanization. For example if the vulcanization is carried out at a pressure of 320 atmospheres (measured 'hot) the gas pressure after vulcanization may be raised to 350 atmospheres (measured cold) if necessary by forcing additional gas into the 'ner, while it containsgas at higher pressure,

since the absorption of gas by materials of the same nature remains sensibly constant.

In is"continuously subk-ted to the 5 stressed by its 35 load-. In fact it used in tensi'oned con-- 7o.

their inner edges '76 tend to pro ect upward into-the inside of In thisnianner'- ,there can be easily manufactux-ed a filling which after the removal of the external gas pressure contains a much greater internal pressure than that corresponding to the pressure inthe tire. It is thus easy to accommodate the necessary amount of fillin in the tire for the inflation of the same and theinsertion of the filling. offers no difliculties, its volume being smaller than the space within the tire. It is thus possible to lodge the beadingsor edges of the tire in their correct positions, an necessary to secure-thecover by means of thumb screwsl I After the ins ofth dilling 'thetire is-heated in a lse l box, preferably by means of hot air, to.:J7O,to 9O;.C. for a half to one hour according tof thf size'of section. Owing to the effect =.ofxthe heat the filling material becomes plastic, soathat it is ex-' panded by the gas occludedthe'rein until it bears firmly against the inside ofthe cover v andstretches the same stifliyl "The'tension is now, indistinction to the previously described methods'of inserting the filling, removed from the-filling and transmitted to the fabric of the cover,whereby the latter is 'powerfully stretched. Owing to this-the "expansion of" the filling is available for the working efforts, that is the filling is no longer over-stressed even by considerable stresses due'to working, and withstands these loads permanently without becoming destroyed. Furthermore correctly in they grooves of the rim, since the inflation of the tireis not materially differentfrorn the inflation of an ordinary pneumatictir'e. v

The above mentioned effect of relieving the filling from the tension and the transmitting of the same to the fabric of the cover can be still further increased by subjectin the t'ire while still heated to a vacuum. The effective pressure of the filling is then increased by one atmosphere, the cover 'still further stretched, and the filling still further relieved of ten'sion,-so that the filling after removal from the vacuum is not subjected to expansion even when the cover vis loaded,"

Tire fillings manufactured in this manner possess a high degree of elasticity, are excep'tionally lightyrunning, and have a much longer life than the fillings previously used.

The expansion caused'by the working'of the conditions a tire has only a 'smallefiect on the ofpressure of thetire.

Vai-ious modifications and changes may can be partly vulcanized in stead of raw,

sure previously applied.

fillings whicl comprises the beadings lodgebe made in my process,[su h as the materiag the material. can be cooled under .a cool gas pressure higher than the hot high gas presduring vulcaniza-' tion', withoutj'departin from the spirit of 'theinvention or sacri ci'ng any of its ad-.

vantages. Havin what I c aim as new and desire to secure by LettersPatent is:

-1. The process of manufacturing froth fillings whicn comprises the steps ofvulcanthus fully described my invention,

izing vulcanizable material under a hot high gas pressure, a cool-gas pressure at least equal to'the gas' pressure applied during vulcanization, inserting'the cooled filling into a casing, and

then heating the filled casing to expand the then cooling the-same murder filling until itbccupies the interior of the casin 2. The process of manufacturing froth fillings which comprises the steps offvu'lcanizing vulcanizable material under. a-hot high gas pressure,

then cooling th a Es under a cool gas pressure at'least equaLto the gas pressure applied during vuleaniza tion, insertmg'the cooled filling into a mising, heating the casing and subjecting the heated casing to a vacuum to further'exparid the filling.

,3. The process of manufacturing froth the ,stepsof vulcanizing vulcam' zable material under a hot high gas pressure,'then cooling the same under; I a cool ga pressurehigher than the'gasprjessure i applied during vulcanization, inserting the cooled filling" into a casing, and then heating the fille casing to expand the filling until itbccupies 'JFRITZ PFLEUMER.

. Witnesses:

PAUL AREAS,

CLARE} SIMON.

the interior of the, 

